Question 694803
There are 13 diamonds in a pack of cards and 4 queens. BUT one of those queens is the queen of diamonds which has already been taken account of in the 13 diamonds. That gives a total of 16 cards in the pack which are diamonds and queens.

So the chance (probability) that you could choose one of those is 16 out of the 52 cards that are in the pack. (16 over 52)

Cancelling this down (simplifying) gives   4 over 13.

(Sorry, but I don't know how to type fractions in this answer box!)